A capacitor in the periphery of CPU (central processing unit) used for personal computers and the like is required to be suppressed in the fluctuation of voltage and in order to reduce the heat generation at the passing of a high ripple current, have high capacitance and low ESR (equivalent series resistance).
In general, two or more aluminum or tantalum solid electrolytic capacitors are used.
Such a solid electrolytic capacitor is constituted by an aluminum foil having fine pores in the surface layer or a tantalum powder sintered body having fine pores in the inside, which serves as one part electrode (electric conductor), a dielectric layer formed on the surface layer of the electrode, and the other (counter) electrode (usually a semiconductor layer) provided on the dielectric layer.
With respect to the method for forming the semiconductor layer of a capacitor using a semiconductor layer as the other (counter) electrode, for example, a method of forming the semiconductor layer by means of energization is described in Japanese Patent Nos. 1,868,722, 1,985,056 and 2,054,506. This is a method of dipping an electric conductor having provided on the surface thereof a dielectric layer in a semiconductor layer-forming solution and applying a voltage (passing a current) between the electric conductor serving as the anode and an external electrode (cathode) prepared in the semiconductor layer-forming solution, thereby forming a semiconductor layer.